Additive manufacturing may be used to quickly and efficiently manufacture complex three-dimensional components layer-by-layer, effectively forming the complex component. Such additive manufacturing may be accomplished using polymers, alloys, powders, solid wire or similar feed stock materials that transition from a liquid or granular state to a cured, solid component.
Polymer-based additive manufacturing is presently accomplished by several technologies that rely on feeding polymer materials through a nozzle that is precisely located over a preheated polymer substrate. Parts are manufactured by the deposition of new layers of materials above the previously deposited layers. Unlike rapid prototyping processes, additive manufacturing is intended to produce a functional component constructed with materials that have strength and properties relevant to engineering applications. On the contrary, rapid prototyping processes typically produce exemplary models that are not production ready.
Heating of the feed or filler material in the nozzle in additive manufacturing is generally accomplished by direct contact between a polymer feed stock and a heating element, typically a resistively heated metal cylinder at elevated temperatures. Likewise, in additive manufacturing, unlike rapid prototyping, the entire component under construction is typically maintained at an elevated temperature in a chamber or furnace until the build is complete. Keeping previously deposited layers at elevated temperature improves the adhesion between the component and newly deposited material while minimizing macroscopic distortion. There are inherent limitations to this technology that prevent higher deposition rates, out of furnace printing and control of microstructural defects (such as pores).
In addition, existing additive manufacturing processes, including fused deposition modeling (FDM), typically exhibit a thermal lag associated with heating a deposition nozzle. Typical fused deposition modeling systems obtain thermal stability by maintaining a massive resistive heater at a constant temperature resulting in slow response.
Magneto-thermal conversion is the conversion of electromagnetic energy into thermal energy. In ferromagnetic magnetic materials, a principle mechanism underlying magneto-thermal conversion is related to externally induced disturbances in the magnetic structure and how strongly the materials resist these disturbances. The dissipated electromagnetic energy is the product of these two and can be transformed into thermal energy among other forms. Therefore the external field should be sufficient to induce disturbances in the magnetic structure while the magnetic material should provide sufficient resistance to dissipate energy yet not resist so strongly that the external fields cannot induce disturbances. It is therefore desired to match the magnetic response of a material with the correct amplitude and frequency of electromagnetic energy. In soft magnetic materials, there is a minimal energetic barrier to either rotate the moment within a domain, or nucleate a reversed domain and move the resulting domain as opposed to hard magnetic materials that resist such disturbances. The energy product associated with magnetic materials is a function of the coercivity, remnant magnetization and magnetic anisotropy. In general, materials with coercivity ≥1000 Oe can be classified as hard ferromagnets. Soft ferromagnets have lower coercivity, and good soft ferromagnets have coercivity <1 Oe. Intermediate materials having a coercivity >1 Oe and <1000 Oe are useful in applications where a magnetic hysteresis losses are required in applications such as, for example, transformation of electromagnetic energy into thermal energy, also known as magneto-thermal conversion